Sulfur slurry preparation and transportation in pipelines

ABSTRACT

AN IMPROVED SULFUR-LIQUID PETROLEUM FRACTION SLURRY RESISTANT TO AGGLOMERATION BY ADDITION THERETO OF A SMALL AMOUNT OF A POLAR-CONTAINING SURFACTANT EXTRACTED FROM CRUDE OIL.

United States US. Cl. 252-309 4 Claims ABSTRACT OF THE DISCLOSURE An improved sulfur-liquid petroleum fraction slurry resistant to agglomeration by addition thereto of a small amount of a polar-containing surfactant extracted from crude oil.

The invention relates to an improved and novel process of preventing sulfur agglomeration, sticking, deposition and plugging of pipelines transporting sulfur in the form of a solid sulfur-liquid hydrocarbon slurry.

CROSS-REFERENCE This application is a division of co-pending application Ser. No. 784,926, now US. Pat. No. 3,582,148.

BACKROUND OF THE INVENTION The transportation of sulfur neat or as a water or oil slurrying pipelines is well known in the art as noted by reference to US. Pats. 2,798,772; 2,917,345 or 2,947,578 or as described in Pipeline Industry, June 1967, pages 58- 60. In making the sulfur into a sulfur-hydrocarbon slurry, the sulfur is generally sprayed in molten form intoeither water or a hydrocarbon to form a slurry suitable for transportation through a pipeline. Formation of a stable slurry wherein the sulfur does not undergo any undesirable change or the slurry does not exhibit a tendency to wide variation in viscosity is essential to the process in addition to other problems which may be encountered during and after transportation of the slurry through a pipeline. Thus, agglomeration and separation of the sulfur from the carrier fluid, plating, depositing or coating of the sulfur on pipeline walls causing plugging of the pipeline, corrosion, viscosity changes due to pressure and temperature variations requiring greater pumping power which increases operation costs, etc., are only a few of the problems normally encountered in transporting sulfurliquid hydrocarbon slurries through pipelines.

Although the above are serious problems for consideration in transporting sulfur through pipelines, nevertheless the transportation of sulfur in slurry form through pipelines can be made to be an effective, attractive and economic means of sulfur transportation, particularly since sulfur is recovered or obtained from isolated, remote and inaccessible areas, and must be transported to desired accessible areas. As noted above, a number of methods have been proposed for pipeline transportation of sulfur slurries such as injecting molten sulfur into water or a liquid hydrocarbon thereby forming a sulfur atent r Patented July 10, 1973 slurry for pipeline transportation. These methods for making sulfur slurries suitable for transporting through V pipelines generally do not overcome the agglomeration, deposition, sticking coating and/or plugging problems described above.

An object of the present invention is to transport sulfur as a sulfur-liquid hydrocarbon slurry through pipeline which is stable and fiowable.

Still another object of the present invention is to trans port through a pipeine sulfur-liquid hydrocarbon slurries without causing sulfur agglomeration, coating, deposition or plugging of the pipeline.

Still another object of this invention is to form a slurry of sulfur in a liquid hydrocarbon medium, which when formed is stable, does not tend to cause sticking, agglomeration or plugging of equipment during the making of the slurry or on storage or cause any difiiculty in circulation of the slurry when said slurry is pumped and transported through a pipeline and from which the sulfur can be readily recovered at the terminal end of the pipeline as essentially pure sulfur.

Another object is to transport sulfur as a liquid hydrocarbon slurry by pipeline over great distances under conditions of reduced pumping and handling costs.

Other objects will be apparent from the following description.

SUMMARY OF THE INVENTION The present invention is directed to an improved, novel and new technique for making a sulfur-liquid petroleum slurry and transporting a slurry of a sulfur-liquid petroleum through pipelines over great distances without causing sulfur agglomeration or sticking during the slurry preparation or on its subsequent storage if necessary or when pipeline transporting the slurry so that sulfur deposition on the walls of the pipelines due to the tendency of sulfur under such conditions to adhere to the pipeline walls because of temperature, pressure and other variable conditions so as to plug said lines is inhibited or prevented; by admixing or adding during the making Of the slurry or injecting or adding prior to or after injection into the pipeline of a slurry of sulfur and a liquid petroleum a small amount of natural surfactant components present in crude oil which can be refined 0r unrefined crude oil. The amount of crude oil in the liquid petroleum ranges from 0.1% to 10%, preferably between 0.5 to about 5%. The natural surfactants present in crude oil include the natural polar-containing constituents present in crude oil such as the nitrogen-, oxygenand sulfurcontaining materials and active hydrocarbons possessing surfactant properties and the materials can be added to the slurry of sulfur and liquid petroleum as described prior to or during the making of the slurry or these active surfactant materials can be injected when necessary in various places along the pipeline where indications are that the slurry might cause sulfur agglomeration, deposition, sticking or plugging of the line. Any plugging detection means known in the art can be used for this purpose. It has been noted that by adding or injecting into a slurry of the sulfur and liquid petroleum in which the sulfur content of the slurry can vary from about 10% to about 60% by volume or higher, preferably between 30 and 50% sulfur, e.g., kerosene or oil condensate or crude oil during or after the slurry preparation, of from about 0.1 to of crude oil containing naturally an active surfactant material, that these active surfactant materials not only prevent plugging or pipelines transporting said slurry but also preventing agglomeration of sulfur, sticking during the slurry preparation and deposition of sulfur on the walls of the pipelines and improves flow of the slurry and reduces pumping costs.

The sulfur-liquid petroleum slurry can be made by any suitable means such as described in U.S. Pat. 2,798,772 or by the method described in U.S. Pat. 3,443,837. It is preferred that in the making the sulfur-liquid petroleum fraction slurry that the sulfur is produced in spherical form since sulfur in this form in the slurry is more stable and is resistant to agglomeration, separation, attrition and friction.

The phase transfer method for making the sulfur slurry as described in the above-mentioned copending application comprises first forming a sulfur-aqueous liquid (water) slurry and thereafter phase transferring the sulfur particles from the aqueous liquid into a liquid hydrocarbon. Thereafter, the crude oil can be added as desired.

The liquid petroleum carrier for the sulfur can be one ranging in viscosity from a light petroleum fraction such as liquefied petroleum gas (LPG), gasoline, kerosene, fuel oil, lube oil, petroleum distillates, condensates, crude oil and mixtures thereof. Preferred are liquid petroleum containing at least 10% or higher of aromatics, preferably about -30% aromatic enriched kerosene or oil con densate fractions or crude oil containing 15-20% aromatics which include monoand polyaromatic hydrocarbons.

The surfactant crude oil components can be obtained from unrefined or refined crude oil or crude oil rich in said surfactant materials can be used. By unrefined crude oil is meant any crude oil which has not been processed in a refinery. A crude oil containing from .001 to 10% by weight or higher of natural surfactant materials may be used as it is removed from the ground, or it may be first processed in field units such as oil-water separators, degasers, etc. Although just how these surfactant components of crude oil function in the sulfur slurry is not understood, it has been found that these crude oils contain surface-active components or agents which prevent sulfur agglomeration, sticking and aids in the formation of spherical sulfur particles having dimensions of from 10 to 800 microns and preferably between 100 and 700 microns.

The surface-active components include the polar-containing materials such as the nitrogen-, oxygen and'sulfur-containing compounds present in crude oil as well as active hydrocarbon compounds, e.g., petroleum resins, can be extracted from the crude suitable means such as described in Chapter 4 of Petroleum and Its Products by Vander Hare, etc., or in Chemical Technology of Petroleum, Chapter 2, by Gruse and Stevens or these surface-active materials can be obtained by processes described in U.S. patents (I) 2,919,237; 2,992,181; 3,074,882; 3,294,678 or (II) 3,119,764 or (III) 2,729,595; 2,741,578; 2,925,379 and 2,980,606. In the case of the U.S. Pat. 3,294,678 the highly asphaltic crude and distillates thereof can be used per se as the additive. Crude oils rich in said surface-active components can be used provided such crudes are added to the slurry in concentrations such that the surface-active components are present in amounts of at least 0.1% and preferably l-2% based on the finished slurry preparation.

During the preparation of the slurry as the molten sulfur is dispersed into liquid petroleum containing active components to aid in the making of spherical particles as well as prevent agglomeration, sticking and the like, the slurry can be cooled effectively by vapor cooling such as described in U.S. Pat. 2,632,691 or by use of volatile organic materials such as low molecular weight hydrocarbons or chlorinated hydrocarbons in which case the process should be carried out under pressures as described in U.S. Pat. 2,316,673.

At the terminal end of the line the sulfur can be readily separated from the slurry by any suitable means.

PREFERRED EMBODIMENT OF THE INVENTION (1) A 4060% sulfur-aromatic (17%) enriched kerosene slurry was prepared by phase transfer by first injecting molten sulfur into an aqueous liquid such as water and thereafter contacting the slurry thus formed with the aromatic enriched kerosene to effect phase transfer of the sulfur particles into the aromatic enriched kerosene. To the sulfur-kerosene slurry was added from about 1% to about 2% surface-active components of crude oil and thereafter this slurry was injected into a pipeline for transportation to a terminal station. Sulfurkerosene slurries containing a small amount of crude oil thus formed do not form agglomerates or did they plug the pipeline. Instead of using the phase transfer technique for making the slurry, molten sulfur can be injected into the kerosene into which a small amount of crude oil (0.1 to 10%) containing naturally occurring surfaceactive components has been premixed.

(II) An advantage of the present process for transporting through pipelines sulfur-liquid petroleum slurries as defined is that the slurry can be also prepared by direct injection of molten sulfur into a suitable petroleum such as kerosene, fuel oil, oil condensate or distillate or crude oil and mixtures thereof to which has been previously added a small amount of surface-active components of crude oil so as to aid in making spherical sulfur particles and prevent sulfur agglomeration, deposition and plugging of pipelines. Either process as Well as other processes can be used to make the sulfur-liquid petroleum slurry depending on the availability of the carrier. Thus, where water is available the first process can be used and if not the second one can be used.

The presence of a small amount of surface-active components of crude oil during the preparation of the slurry by method (I) or (II) has an additional advantage in that these surfactants aid in the formation of spherical sulfur particles which are most desirable since spherical sulfur particles in slurries as defined provide optimum pipeline performance such as low pressure drops during its transportation and ease of recovery and purification at the terminal end of the pipeline.

The following examples illustrate the essence of the present invention.

(A) Molten sulfur at -160 C. Was sprayed into aromatic (17%) enriched kerosene through a spray nozzle at about 200 p.s.i. pressure drop to give a homogeneous slurry with sulfur solids content of about 16% volume in which the sulfur particles were essentially large angularcrystalline particles which began to stick together and agglomerate into a sticky mass within about 10-15 minutes.

(B) The method of (A) was repeated except that 1% of surface-active components of crude oil were added to the kerosene carrier. The particles formed were microspherical (20-450 microns) in shape and no tendency of the particles to stick to agglomerate were observed for over 24 hours.

In another test different petroleum fractions were made to form sulfur slurries wherein a 90-ml. portion of molten sulfur at C. was injected as a continuous stream for 0.5 minute into a well-stirred 500 ml. charge of a petroleum carrier. As shown in Table 1 some of the carriers were used neat and to some were added crude oil. For comparison various surfactants were added to sulfuroil slurries and the results are shown in Table 1.

Conditions: 500 ml. carrier in l-liter Morton flask. 90 ml. sulfur at approximately 140 0. added in 0.5 minute. 1,200 r.p.m. with crescent blade stirrer Coagulum Initial Level, (+12 mesh), temp, percent percent weight Particle Run Carrier 0 weight Type basis S fed -16, -30, +50 (iron shape n 1 Petroleum fraction (Water- 22 None 19. 1 57. 7 19. 3 680 A ton condensate).

d 22 1 Bryton 430 (62% alkylaryl 20. 4 60. 0 21. 0 710 A lfonate) 24 1 Oleic acid 30 72. 0 13. 7 770 A. 23 1 Naphthenic acid b0 30 A 23 1 Dehydroabietic acid 30 A 21 l 50% dodecyltrimethyl- 13. 8 62. 6 20. 8 700 A ammonium chloride. 7 kerosene/white oil 23 0. 1 Surface-active components 7. 0 64. 6 24. 0 690 S (Waterton condensate) of crude oil. 8 d0 4 24 1 Residue resins 6. 3 64. 1 25. 8 680 S=spherical, A=agglomerated, in estimated order of abundance in +30 mesh fraction.

b 600 r.p.m.s in early scouting runs and in all 60 0. runs.

a Derived from Canadian oil field. API gravity=54.9; viscosity, is. 59 F.==0.953 and 77 F.=0.865; flash point, tag open cup, F.=7; pour point, F.=80; sulfur, percent weight total=1.14; FIA, percent volume saturates=82 and aromatics=18.

API gravity=54.9; viscosity cs. 59 F.=0.953 and 77 I .=0.865; flash point, tag open cup, F.=7: pour point, F.=80; water percent weight=0.16.

sulfur, percent weight total (X-ray) =l.14e1ementa1=0.0011-sulfide=0.060 and mercaptan=0.172; FIA, percent volumo saturates=82 and uromatics=18i Sulfur slurries of the present invention containing small amounts of surfactant crude oil additives as described can be transported through pipelines over great distances with out the danger of sulfur deposition, agglomeration, sticking or plugging of the pipelines.

At the terminal end of the line the sulfur can be removed from the liquid hydrocarbon by suitable means such as described in US. Pat. 2,798,772 and the sulfur purified by methods as described in US. Pat. 2,809,885 or as described in U.S. Pat. 3,489,677 which comprises treating oil contaminated sulfur with an aqueous solution containing a mixture of alkali hydrosulfide and corresponding hydroxide, e.g., ammonium hydrosulfide and ammonium hydroxide or by other suitable means such as sulfur can be recovered from oil slurry by filtration of molten sulfur and liquid-liquid extraction with a hydrocarbon solvent containing l0-50% aromatic. Thus, at the receiving ter minal the sulfur slurry can be filtered and washed. The recovered sulfur is then melted and purified by liquidliquid extraction with an aromatic hydrocarbon such as cumene. Also, if desired, the filtered sulfur can be steam stripped to recover bright yellow sulfur.

The foregoing description of the invention is merely intended to be explanatory thereof. Various changes in the details of the described method may be made within the scope of the appended claims without departing from the spirit of the invention.

We claim as our invention:

1. A stable non-agglomerating sulfur-liquid petroleum slurry comprising from about 10% to about sulfur, based on total slurry, in a petroleum condensate and in cluding, from about 0.1% to about 10% of a polar-containing surfactant extracted from crude oil.

2. The composition of claim 1 wherein the petroleum condensate containing 15-30% aromatics.

3. The method of claim 2 wherein the surfactant is present in amounts of 0.5-5

4. A stable non-agglomerating sulfur-liquid petroleum slurry comprising from about 10% to about 60% sulfur, based on total slurry, in a petroleum condensate and from about 0.1% to about 10% of a polar-containing surfactant selected from the group consisting of nitrogen-, oxygenand sulfur-containing compounds present in crude oil.

References Cited UNITED STATES PATENTS 2,111,552 3/1938 Chambers et a1. 424-164 2,643,202 6/1953 Burton et al. 252309 U X JOHN D. WELSH, Primary Examiner US. Cl. X.R. 

